Being applications for driven wheels, not having a pass-through shaft along the bearing axis, such related sealing devices have an axi-symmetric cup shape, so that to wrap up the bearing outer ring. Since the bearing outer ring is stationary, such devices perform a static sealing, protecting the bearing from any environmental contaminant (water, mud, debris and so on).
Generally speaking, the sealing device comprises a metallic screen, substantially cup shaped, assembled on a collar of the outer ring of the rolling bearing by means of a press fit operation. In particular, the screen comprises an annular cylindrical wall, whose internal lateral surface is coupled by means of the press fit operation with the external lateral surface of a collar of the bearing outer ring. While in previous embodiments, the sealing device was designed to ensure its function only by means of the coupling with the bearing, in current known embodiments the sealing device has a metallic screen, to whom is steadily fixed an elastomeric sealing element, which externally wraps up the screen and ideally goes on along its profile with an appendage, which protrudes in axial direction and inside the bearing, so realizing a sealing lip.
Document EP 2 466 161 A1 discloses a bearing/hub unit for a motor-vehicle wheel, provided with a stationary bearing outer ring and a bearing inner ring defining together with the outer ring a cavity devoid of any sealing device; an encoder arranged inside the cavity and fixed externally on the inner ring; and a protective cover which is made of non-ferromagnetic material and is mounted on the outer ring to protect the encoder and close the cavity; there being provided a static sealing element which is joined to an outer edge of the protective cover.
Document DE 10 2006 040776 A1 discloses a roller bearing wherein a seat is conically formed for the cylindrical part of the sealing element.
The current geometry of the metallic screen and the collar of the bearing outer ring, particularly, the interference for press fit the surfaces of the two components and the coupling length of the same surfaces, causes, after the assembling, a remarkable conical shape of the annular cylindrical wall of the sealing device. Such phenomenon impacts the sealing quality. In fact, component endurance tests show, as end result, an increase of water infiltration percentages, which reach unacceptable values.